Upgrading two fuse boards to amendment 3 CU

[Diggaboy]

My first post so be gentle. And as I'm not an electrician please be patient also!

Just buying a small cottage (from son) to hopefully convert to a holiday let and obviously the fuse boards need upgrading (see pic). There are two Wylex fuse boxes (one on left supplying four storage heaters), and a Legrand CU (top left) supplying the garage via the SWA at the top of the board.



Before getting an electrician in, a couple of questions:

1. The two Wylex boxes (storage heaters and main house fuses, covers removed for clarity) will be replaced with two amendment 3 CU's. Is it better to move the Legrand CU into the garage, taking it off a spare way in a split load CU (2 RCDs) housing the main house fuses. Leaving it where it is means it will also have to be changed to Amendment 3 CU presumably, but not if it's in a non occupied garage, completely separate and some 15 metres from the house?

2. I want to get the DNO in to install 100A main isolating switch between meter and CU's but presumably with the current setup with meter and time clock, and there are three sets of tails going to the CU's, they'll need to install three isolating switches (or two if garage supply CU is removed into the garage)?

 

[Diggaboy]

Very good of you to say so, but I suspect I just think I know, rather than I actually do know - arguably the worst kind of diy sparky!

Just one more question (promise!) and you can go back to your day job ;-)......

..... you mentioned DNO will need to fit 2 pole isolator. Should that have read 3 pole isolator as shown in your first class diagram?The storage heater CU and 24 hour CU will obviously require separate live feeds, as you've drawn, so there'll need to be two separate lives coming in from the DNO's isolator; one going to each of my two CU's, and also a common neutral, in addition to the two live tails just mentioned?

(I suppose it's an academic question as the DNO will dictate and supply what will be fitted, but it may help if I can specify what's needed before they come out, rather than the network engineer turns up with the wrong isolator, 'should have told us mate..... see you next week, and it'll be another 50 quid!' Hopefully they'll come and look first perhaps.)

 

[YoungScud]

Very good of you to say so, but I suspect I just think I know, rather than I actually do know - arguably the worst kind of diy sparky!

Just one more question (promise!) and you can go back to your day job ;-)......

..... you mentioned DNO will need to fit 2 pole isolator. Should that have read 3 pole isolator as shown in your first class diagram?The storage heater CU and 24 hour CU will obviously require separate live feeds, as you've drawn, so there'll need to be two separate lives coming in from the DNO's isolator; one going to each of my two CU's, and also a common neutral, in addition to the two live tails just mentioned?

(I suppose it's an academic question as the DNO will dictate and supply what will be fitted, but it may help if I can specify what's needed before they come out, rather than the network engineer turns up with the wrong isolator, 'should have told us mate..... see you next week, and it'll be another 50 quid!' Hopefully they'll come and look first perhaps.)

Yes. My bad. It's a two pole and neutral. In fact, if our southern colleagues are using the same supplier as us, which they probably are, it might be a 3P &N, with one Phase terminal unused. I wouldn't envisage there would be a problem with which type they turn up with. Our guys usually carry a stock of different materials, and they will be aware of which tariff is installed at your property (they can tell meter types from the serial numbers, among other things). It is our job to know these things, so no danger of another 50 quid. Just in case anything does go wrong, it wasn't me who trained him!

 

[Diggaboy]

Yes. My bad. It's a two pole and neutral.

My apologies, 'two pole and neutral' .... that's exactly what you said in your original reply! I obviously didn't read it properly and wrongly interpreted it as just 'two pole isolator'.

.....I shall write out a hundred times, 'I must read helpful replies properly next time.....I must read helpful replies properly next time...'

 

[YoungScud]

 

[Diggaboy]

In case anyone's interested, I've just received quote (indirectly) from isupplyenergy of £68 (inc vat). Not seen details of the quote yet, but I assume that's supply and fitting of appropriate isolator (presumably by SP energy).

Slightly more than when the supplier was Npower that arranged an isolator fitting for me....well, £68 more actually as they didn't charge at all 5/6 years ago, but they may well have introduced charging since then I guess.

 

[YoungScud]

To be fair, neither did SP at one time.